Taxonomy

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Taxonomy Classifying Organisms
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The Five-Kingdom System
a.k.a. - prokaryotes
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Levels of Classification
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Binomial Nomenclature

• 2 Part Latin names for living things
• Scientific Names
• Genus Species
• Ex/ Homo sapiens
• We generally use a dichotomous key to name
  organisms

Carolus Linnaeus (1707-1778)
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Binomial Nomenclature (contd)

• Back then the Earth was flat, and living things
  did not evolve
• Now we use PHYLOGENY in combination with old
  knowledge to study evolutionary history

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3 Domains Based on Evolution
Common Ancestor - 3.7 Billion Years Ago
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Classification of Bacteria
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Classification of Bacteria

• Light microscope was the original tool
• Initial classification was based on of the shape
  of the bacterial cells
• Cocci
• Bacilli
• Spirilla
• Spirochetes

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Taxonomy / Systematics

• Identification
• Distinguishing features
• Engine size
• Mileage
• Number of passengers
• Type of transmission

• Classification
• Organization into groups
• Car
• Truck
• SUV
• Van

• Nomenclature
• Providing a formal name
• Genus species
• Ford Crown Victoria
• Chevy Impala
• Toyota Camry
• Honda Civic

Consistent rules for all Scientists
Relevant Meaningful Make biological
sense Evolutionary context
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Domains can be Divided into Many
Sub-classifications

• Domain Bacteria
• Phylum Proteobacteria
• Class Gamma Proteobacteria
• Order Enterobacteriales
• Family Enterobacteriaceae
• Genus Escherichia
• Species Escherichia coli

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Binomial nomenclature Genus species Escherich
ia coli Genus name is always capitalized
Species name is never capitalized coli Both
names are always either italicized or underlined
Abbreviation E. coli
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Old School Medical Microbiologists said

• One bacterium One disease
• So to these scientists, bacteria were also
  classified as to the disease they caused
• But there are several types of E. coli
• So the naming system for bacteria evolved

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Extra Stuff for Naming Bacteria

• strain or variety a culture derived from a
  single parent that differs in structure or
  metabolism from other cultures of that species
• type a subspecies that can show differences in
  antigenic makeup ,susceptibility to bacterial
  viruses, and in pathogenicity
• Four Groups Based on Cell Wall Composition
• Gram-positive cells
• Gram-negative cells
• Bacteria without cell walls
• Bacteria with chemically unique cell walls

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